Chemical Foundations of Life Practice Quiz (11 questions)

1. Which description defines matter?

A. A form of energy that occupies space without mass

B. A substance that has mass but occupies no space

C. Anything that has chemical properties and can be broken down

D. Anything that occupies space and has mass

Answer: (D)

Explanation

Matter is defined by occupying space and having mass. A substance’s ability to be broken down does not determine whether it is matter.

2. Which set lists the four most common elements in living organisms?

A. Carbon, oxygen, hydrogen, and nitrogen

B. Oxygen, hydrogen, iron, and chlorine

C. Hydrogen, nitrogen, phosphorus, and sodium

D. Carbon, oxygen, sulfur, and calcium

Answer: (A)

Explanation

Carbon, oxygen, hydrogen, and nitrogen are the four most common elements in living organisms. Sulfur and calcium are elements, but they are not part of this four-element set.

3. Which arrangement describes the main regions of an atom?

A. A central nucleus of protons and neutrons, with electrons occupying outer orbitals

B. A central nucleus of electrons and neutrons, with protons occupying outer orbitals

C. A nucleus of protons, with neutrons and electrons occupying outer orbitals

D. A central region of electrons, with protons and neutrons occupying outer orbitals

Answer: (A)

Explanation

An atom has a central nucleus containing protons and neutrons, while electrons occupy orbitals in the outer region. The alternative placing electrons in the nucleus confuses the locations of the subatomic particles.

4. Two atoms are isotopes of the same element when how do their structures differ?

A. They have the same numbers of protons and neutrons but different mass numbers

B. They have different numbers of electrons but the same number of neutrons

C. They have different numbers of protons but the same number of neutrons

D. They have different numbers of neutrons but the same number of protons

Answer: (D)

Explanation

Isotopes of the same element differ in neutron number, which gives them different mass numbers, while sharing the same proton number. A difference in proton number instead identifies a different element.

5. What is an electron orbital?

A. A predicted spatial region around the nucleus where an electron may be found

B. A group of three dumbbell-shaped regions within the s subshell

C. The outermost electron shell that determines an atom’s stability

D. A fixed circular path at a specific distance from the nucleus

Answer: (A)

Explanation

An orbital is a predicted spatial region around the nucleus where an electron may be found. A fixed circular path describes the early Bohr model, rather than the meaning of an orbital.

6. What happens in a reversible chemical reaction?

A. Reactants proceed to products until they are used up.

B. Electrons transfer from metals to nonmetals.

C. Some products can convert back into reactants.

D. Atoms share electrons to form covalent bonds.

Answer: (C)

Explanation

A reversible reaction allows some of its products to convert back into reactants. By contrast, a reaction that proceeds in one direction until its reactants are used up is irreversible.

7. What role does hydrogen bonding play in making ice float on liquid water?

A. It arranges water molecules into an open lattice that is less dense than liquid water.

B. It makes water molecules pack more closely together as they form a solid.

C. It increases the mass of each water molecule as the temperature falls.

D. It prevents water molecules from forming attractions with one another.

Answer: (A)

Explanation

Hydrogen bonds organize water molecules into an ice lattice with more open space, so ice is less dense than liquid water. Closer packing would make ice denser, which is the opposite of the effect described.

8. How does water’s adhesion to glass differ from its cohesion?

A. Adhesion dissolves ions in water, whereas cohesion surrounds dissolved ions with hydration spheres.

B. Adhesion attracts water molecules to one another, whereas cohesion attracts water to other materials.

C. Adhesion attracts water to other materials, whereas cohesion attracts water molecules to one another.

D. Adhesion creates surface tension, whereas cohesion makes water move upward in a narrow glass tube.

Answer: (C)

Explanation

Adhesion is attraction between water and other molecules, while cohesion is attraction among water molecules. The two processes are reversed in the most plausible distractor; water’s rise in a tube can occur when its attraction to glass exceeds cohesion among its molecules.

9. Why can carbon serve as a backbone for large biological molecules?

A. It forms hydrogen bonds that link all biological molecules.

B. It has a full outer shell that attracts many hydrogen atoms.

C. It can form up to four covalent bonds with other atoms.

D. It readily forms ionic bonds by transferring four electrons.

Answer: (C)

Explanation

Carbon has four outer-shell electrons and can form four covalent bonds, enabling it to create diverse molecular frameworks. Ionic bonding through electron transfer is not the mechanism that gives carbon its backbone-forming capacity.

10. A hydrocarbon has a carbon–carbon double bond. What structural effect should you expect when comparing it with a similar molecule containing a single bond?

A. The double bond allows free rotation and keeps the attached atoms in a planar arrangement.

B. The double bond allows free rotation and keeps the attached atoms in a tetrahedral arrangement.

C. The double bond restricts rotation and keeps the attached atoms in a tetrahedral arrangement.

D. The double bond restricts rotation and keeps the attached atoms in a planar arrangement.

Answer: (D)

Explanation

A carbon–carbon double bond prevents rotation and holds the atoms on either side in place, producing a planar arrangement. A single bond, rather than a double bond, allows rotation and is associated with tetrahedral carbon arrangements.

11. Which characteristic distinguishes enantiomers from structural and geometric isomers?

A. They differ in the covalent arrangement of atoms within the molecule.

B. They are non-superimposable mirror images with the same formula and bonds.

C. They differ in how atoms are arranged around a double bond.

D. They have different chemical formulas but similar functional groups.

Answer: (B)

Explanation

Enantiomers have the same formula and bonds but form mirror images that cannot be superimposed. Structural isomers instead differ in covalent arrangement, while geometric isomers differ in arrangement around a double bond.